Abstract:Lignin nanoparticles (LNPs) and tea polyphenol (TP) were prepared through self-assembly and infused with a sodium alginate (SA) polysaccharide membrane solution using a blending technique. SA/TP/LNPs composite films were prepared using a casting method. The effects of the LNPs content on the properties of the SA/TP/LNPs composite film and its application in pepper preservation were studied. The prepared LNPs were approximately 98.33 nm thick. The SA film is an excellent carrier for LNPs and TP. With increasing levels of the LNPs, the color of the film gradually deepened, and the light transmittance gradually decreased. The overall performance of the SA/TP/LNPS-5 composite film (LNP mass fraction of 5%) was improved compared with that of the SA film, as the tensile strength increased by 114.67% and the elongation at break and water vapor transmission rate were reduced by 47.81% and 72.04%, respectively. The composite film exhibited inhibition rates of 91.28% against Escherichia coli and 89.20% Staphylococcus aureus. The free radical scavenging rates of DPPH and ABTS were 88.75% and 87.21%, respectively. A preservation experiment demonstrated that the SA/TP/LNPs-5 composite film effectively reduced the weight loss rate of pepper and delayed the consumption of Vc content in pepper compared to the CK and PE film groups. On the 10th day of storage, the weight loss rates were reduced by 49.93% and 39.12%, respectively (P<0.05). The highest Vc content in the SA/TP/LNPs-5 composite membrane group was 54.17 mg/100 g. In summary, this study introduced an environmentally friendly composite film with antibacterial and antioxidant properties, providing novel insights for the application of lignin. The composite film has promising application prospects in food preservation.
